More specifically, I am wondering if there is such an example satisfying the following criteria:
- The example happened after 1888, it would be better to be after 1900—I think few people have the conception of correlation before Galton's 1888 paper.
- The correlation found in the example is not easy to be investigated, but the correlation is non-trivial so that it is published first; then that correlation is investigated further, maybe with much more effort, and is finally confirmed as a result of a non-trivial causal relationship.
- The correlation of $A$ and $B$ is a direct result of the causal relationship between $A$ and $B$, and not induced by a common cause $C$.
I understand that correlation is not causation. Basically, I want to have examples showing that the investigation of correlations sometimes leads to the discovery of really non-trivial causal relationships, and that the conception of correlation really help for those pursuing causality.